I have a screen in my application (login), that may be presented from any other screen
i want to put the logic of starting that screen outside of my ViewControllers, so it is not duplicated
is this possible ?
this screen may also be loaded upon an NSNotificationCenter notification message that i received
So, I'd put this into a controller where each of the view controllers calls this controller to perform the login. When the login is requested, pass the requesting view controller (or its parent if it isn't full screen) as a parameter.
Now, when the login view needs to be presented you have a generic way of presenting it from inside the 'login controller'. The requesting view controllers know nothing about the 'login controller' and the 'login controller' knows nothing about the requesting view controllers.
When triggered by a notification the app delegate can get the root view controller from the app window and pass that as the requesting view controller.
You can just create a ViewController for your login screen and give it a "storyboard id" under the "Identity inspector".
And when you'd want to show it you can instantiate it like this:
loginViewController = [[self storyboard] instantiateViewControllerWithIdentifier:#"storyboardID"];
after that you can either push it if you are using a navigationController or add it as a subview.
EDIT: how do i know if it is present:
NSArray *controllers = self.navigationController.viewControllers;
for (UIViewController* controller in controllers)
{
if ([controllers isKindOfClass:[LoginController class]])
{
NSLog(#"is already present");
}
}
Related
I am working with Parse, and one thing I have implemented in my app is their built in PFLogInViewController. This controller will be presented at two times in the application - when the app first starts and the user is not logged in, and when the user taps the "Log out" button of my application (logging out takes them back to the PFLogInViewController, as you are required to sign in to use the app). I would like to set this up using Storyboard, as that is how the rest of my app is laid out. How could I set up a central view controller (a PFLogInViewController) that is accessed at these two times? I have already Subclassed PFLogInViewController and set it up, I just need advice on how to place it in Storyboard and how to connect it to my views. To make this question help as many people as possible, the general theme of my question is how does one establish a central Login/ViewController that can be accessed at different points in the application using Storyboard. Attached is the basic idea of what I'm trying to accomplish. I haven't been able to successfully segue to the initial TabBarController, and I'm not sure how I should make the LoginController the initial ViewController if I can't segue. I am programming in Swift, if it matters.
There are a few ways to do this depending upon your application. One way is drop a UIViewController onto the storyboard, but don't wire it up to anything (no segue). Create a storyboard id for it such as "MyLoginVC". Do the necessary subclassing of UIViewController and attach the class to your VC. Then, when you want to display the VC simply do the following or wire this up to your logout button
id destinationVC = [self.storyboard instantiateViewControllerWithIdentifier:#"MyLoginVC"];
[self.navigationController pushViewController:destinationVC animated:YES];
In addition, if you want to show the login VC as the very first VC when you launch your app, then perhaps in your AppDelegate
// Load Root view controller
UIStoryboard *storyboard = [UIStoryboard storyboardWithName:#"Main" bundle:nil];
self.rootVC = [storyboard instantiateInitialViewController];
self.window.rootViewController = _rootVC;
[self.window makeKeyAndVisible];
// Load Login view controller
id initialVC = [storyboard instantiateViewControllerWithIdentifier:#"MyLoginVC"];
[initialVC setModalPresentationStyle:UIModalPresentationFullScreen];
[_rootVC presentModalViewController:initialVC animated:NO];
When you finish with your login VC (i.e. successful login) then within login VC
[self dismissViewControllerAnimated:NO completion:nil];
and alternatively instantiate your first VC with something similar to the following from within login VC. Note, since you loaded the root VC above first, it is already there with the login VC sitting over it. When you dismiss login VC, the underlying root VC should be ready to rock and roll. Otherwise you can do the following:
- (void)prepareForSegue:(UIStoryboardSegue *)segue sender:(id)sender
{
RootTabBarController *tbController = (RootTabBarController *)[self.storyboard instantiateViewControllerWithIdentifier:#"rootTabBarController"];
[self presentViewController:tbController animated:YES completion:NULL];
}
I think what you want is an unwind segue. Here are the instructions I follow for an unwind segue: https://github.com/bradley/iOSUnwindSegueProgramatically
If the link dies, here is what it said:
In your storyboard create two view controllers.
Subclass UIViewController twice, once for each of the view controllers in your storyboard.
Connect these view controllers to the view controllers in your storyboard.
Make a segue between the first view controller and the second by control+dragging from the first to the second.
Click on the segue you created and give it an identifier in the attributes inspector.
Make a button on the first view controller and link it to an IBAction in its UIViewController subclass.
When this button is pressed, the second storyboard should appear. To make this happen (we are doing it programatically) put the following into the implementation of the action you just created:
[self performSegueWithIdentifier:#"nameOfTheSegueBetweenOneAndTwo" sender:self];
Create a second method in the implemention of the first view controller with the following:
- (IBAction)returnToStepOne:(UIStoryboardSegue *)segue {
NSLog(#"And now we are back.");
}
This method will work to unwind any view controller back to this view controller. Notice that we implement the method in the view controller we wish to return to.
Go back to the storyboard. Focus in on the second view controller. If it is active, you should see a dark bar beneath it with 3 symbols on it. One of these is orange and when hovered over will show the name of the UIViewController subclass that this view controller represents. Control drag from this symbol woth the green symbol that means 'Exit'. You should see all available segue unwinds, which XCode automatically enumerates when you create segue unwind implementations inside UIViewController subclasses that you have shown on your stroryboard. Hence, you should see the segue 'returnToStepOne' as an option. Select it.
In your storyboard's document outline, find the section for the second view controller. You should see an item listed below it with a grey symbol that says something like "Unwind segue from ... to Exit." Click on this item.
Important and easily missed step follows!
On the right side of your storyboard, in the attributes inspector, you should see two fields. One for 'Identifier' and one for 'Action'. In most cases, the 'Action' field will have the text 'returnToStepOne:', which is what we want, but the 'Identifier' field will be blank. Fill this field with the text: 'returnToStepOne' (note that we leave out the colon).
Create a button on the second view controller and link it to an IBAction in its UIViewController subclass.
In the implementation for the method you just created, put the following code:
[self performSegueWithIdentifier:#"returnToStepOne" sender:self];
Run the application. You should now be able to unwind from the second view controller to the first.
I have a UIBarButtonItem that I want to act as a logout button. When the user presses I want to popToRootViewController to take the user back to the login screen. When I call popToRootViewController nothing is happening. self.navigationController is not showing nil in print statements. I have a base view controller that all of my view controllers inherit from. I am attempting to have this logout functionality in the base view controller so all inherited view controllers don't need to also implement it. Is the fact that this is attempting to be implemented in base view controller a problem?
- (void)logoutBtnClicked {
[self.navigationController popToRootViewControllerAnimated:YES];
NSLog(#"nav: %#", self.navigationController);
}
Also, the logoutBtnClicked is being called I know.
When my App is starting I have a modal view controller to enter credentials (IP#, username, password...). When the user is logged he can open many UIViewControllers that can open others UIViewController and so on... These view controller can be navigation controller, tab bars, modals....
Next, the user can leave the application in background. Next, user can open the Mail App and open a mail that contains an attachment to navigate to my App. When the user select my App to open the attachment.
When the App moves in foreground I need to go to a specific viewController of the hierarchy (the first ViewController opened after the login screen).
To move the App to this first ViewController I have tried to use
– dismissViewControllerAnimated:completion:
but without success, there're still a view from the hierarchy that is still displayed.
Any idea how to do this?
Regards,
Sebastien.
If all the view controllers are in 1 Navigation controller and pushed onto the stack, you can simply use either popToRootViewControllerAnimated: or popToViewController:animated:
Otherwise, why not dismiss the first Modal view controller, then put it back with the view controller you want.
I found a solution with this small piece of code
UINavigationController* navc = (UINavigationController*)viewController.topViewController;
if (navc != Nil) {
if (navc.presentedViewController != Nil) {
[navc dismissViewControllerAnimated:FALSE completion:Nil];
}
[navc popToRootViewControllerAnimated:TRUE];
}
It was not complex at the end!
Sébastien.
In the past my app has had only 1 main view controller (MainViewController) and a login view controller (LoginViewController) but now I am moving to a Tab Bar Controller.
Before I was able to do a simple check viewDidLoad of MainViewController for the existence of a username and password in the key chain. If a username and password was not present I used a segue to pop up a modal login view controller.
With the new setup of using a Tab Bar Controller I still only have 1 view controller (MainViewController) which is the root view controller (as of now) and I am trying to do the same thing where it pops up modal of the login screen.
Now when I call the segue in the viewDidLoad of MainViewController:
[self performSegueWithIdentifier:#"loadLoginView" sender:nil];
I am getting this error:
Warning: Attempt to present <LoginViewController: 0x1757cd80> on <UITabBarController: 0x17571e50> whose view is not in the window hierarchy!
But if I associate a button to a method that loads the LoginViewController by way of a segue it works fine. I am doing that in the MainViewController like this:
-(void)loadLogin
{
[self performSegueWithIdentifier:#"loadLoginView" sender:nil];
}
I can see from the error message that when I try to perform the segue from the viewDidLoad of MainViewController it's trying to load the LoginViewController from UITabBarController.
Why can I not load the LoginViewController from the viewDidLoad of MainViewController?
Any help with this would be great.
Thanks!
It looks like -viewDidLoad is getting called before your view controller stack is added to the window. Two things you could try are:
Delaying until the next time through the run loop (this should give the view controllers time to get in place) [self performSelector:#selector(loadLogin) withObject:self afterDelay:0];. This method won't allow you to call a method with two arguments directly
You could use -presentViewController: animated: completion:. This will cause your login controller to slide in from the bottom.
I have a root view controller (RVC) that opens up a Modal ViewController (MVC). I then navigate within the MVC to few more VC's via a push. What is the best practice to get from one of those VC's back to the RVC?
Normally I have a delegate from the Modal VC that calls up to the RVC which then dismisses the modal, but if you navigate away from it, but I'm not sure how I would do that if you navigate away from it.
Without seeing any code it is a bit hard to help but let me shoot in the dark here.
I will assume that the first controller presented inside the modal view provides the protocol/delegate to call the dismiss action.
If you use UINavigationController inside your modal view to push other view controllers on the stack you can always obtain the first controller like this
UIViewController * yourFirstController = [[[self navigationController] viewControllers] objectAtIndex:0];
// and then use your delegate to call your dismiss method
// you will need to typecast your controller based on your subclass otherwise will get warning here
if ([[yourFirstController delegate] respondsToSelector:#selector(yourCloseProtocolMethod)]) {
[[yourFirstController delegate] yourCloseProtocolMethod];
}
Don't forget that a delegate doesn't have to be a property of a UIViewController inside your model navigation stack. Consider creating a singleton class that holds a reference to the rootviewcontroller as a delegate. That way any class in your application has access to it and you aren't forced to continually pass it through to every UIViewController that requires it.